Conformal Carrollian symmetry has been discovered to be isomorphic to Bondi-Metzner-Sachs (BMS) symmetry in generic dimensions [1]}, following closely related observations in two dimensions [2]}. BMS groups emerge as the asymptotic symmetry groups for asymptotically flat spacetimes at null infinity [3]}, [4]}. These groups are infinite-dimensional in dimensions three [5]} and four In higher dimensions, depending on boundary conditions the BMS can be truncated to the Poincare algebra or can still remain infinite dimensional [6]}.. A considerable body of research has been built up relating asymptotic symmetries, soft theorems and memory effect following the lead of Strominger [7]}. The formulation of holography for asymptotically flat spacetimes has followed two routes, Celestial and Carrollian holography. In the Celestial formulation, it has been proposed that a 2d conformal field theory living on the celestial sphere can compute scattering amplitudes in 4d asymptotically flat spacetimes. This has led to novel results about asymptotic symmetries and soft theorems. See [8]}, [9]}, [10]} for recent reviews on Celestial holography and references therein. Carroll holography on the other hand postulates codimension one holography between flat spacetimes and a Carrollian CFT living on the null boundary of flatspace [2]}, [12]}, [13]}. This has seen quite a bit of success, particularly in lower dimensions. See [14]}, [15]}, [16]}, [17]}, [18]}, [19]}, [20]}, [21]}, [22]} for a non-exhaustive list of important contributions in this regard. The connection between 4d scattering and 3d Carrollian CFTs has been recently proposed in [23]} drawing inspiration from the Celestial approach See also [24]} for further connections between the Celestial and Carrollian formulations of flat holography..
